The present invention relates to small power assist machines, more specifically to a walk behind loader for operating working attachments.
Power assist machines have been in existence for a number of years. These machines are found in a variety of sizes and take many forms depending upon the tasks for which the machines are designed. Typically, the power assist machines include a plurality of pneumatic support wheels and a cab or seat and foot pedals for the operator of such a device. Such machines are most commonly equipped with a bucket or skid with which material may be moved. Some of the machines are even provided with one or more attachments, which increase the utility of such devices.
While these machines have great utility, they have drawbacks. One drawback of such machines is that they are relatively heavy. This means that the small support wheels, usually having pneumatic tires, have a rather high ground contact pressure and tend to become mired in soft ground. A popular after market attachment for such machines are pairs of endless tracks that are configured to be placed about the tires on the wheels. The tracks are an added expense, they are cumbersome and heavy. Additionally, attachment and removal requires that the machine be taken out of service. They also can become dislodged and disengaged due to misalignment, underinflation of the pneumatic tires, insufficient tensioning of the tracks, stretching of the track due to wear and tear and the like.
Another drawback, related to a limitation of size, is that of auxiliary counterweights. Some of the prior art machines offer auxiliary counterweights, which are used to increase the rated load carrying capacity. However, these weights are usually attached only onto the rear of a machine and serve only to increase the lifting capacity thereof. This is usually tolerated because there is usually only a bucket or other accessory whose lifting requirement needs to be counterbalanced. However, there is no provision for counterbalancing accessories that require front ends of lift arms to provide competing or downward pushing force.
The present invention relates to a small walk behind loader or apparatus for operating working attachments. The loader includes a ground engaging carriage with a pair of longitudinally aligned wheels or products on each side of the loader. Each pair of wheels drivably supports an endless track. A support frame is attached to the carriage and includes a pair of rearwardly and upwardly extending side members with rear end portions that support rear ends of a lift and a control station. The boom is mounted over center portions of the frame and has a curved or arcuate shape in side view and is positioned so that it extends forwardly relative to the seat end portions of the side members, with the forwardly extending end of the boom configured to removably receive and supply power to a working attachment. The control station includes levers operation linkages which are connected to two separate power motors which enable independent operation of each pair of longitudinally aligned wheels of the ground engaging carriage. The linkages of the controller are automatically urged or biased to a predetermined position in which the drive motors are effectively disengaged from the respective pairs of linearly aligned support wheels. The apparatus also includes at least one selectively positionable counterweight that can be moved relative to the vertical axis of the center of gravity of the loader to increase the operational parameters of the apparatus that is, having the ability to shift the counterweight to counter balance loads to be lifted in one position, and to provide counterweight for compaction or, tamping or drilling forces in a second position.
A feature of the present invention is that at least one counterweight may be selectively positioned relative to the vertical axis of the center of gravity of the apparatus. The curved or arcuately-shaped boom facilitates observation of working attachments at the front end of the boom.
The actuators, couplings, and their attendant power transmission conduits for operating attachments and boom lift cylinder are positioned within the interior space of the boom where they are less subject to damage.
The loader of the present invention is able to traverse and operate in relatively small spaces and has the ability to operate and supply power to a wide variety of working attachments.